Tools for clamping and aligning boiler tubes when connecting the ends of the boiler tubes by welding are known as disclosed in U.S. Pat. Nos. 4,493,139, 4,579,272 and 4,722,468. The devices disclosed in the above-mentioned patents include structures for securing boiler tube ends in aligned and adjacent relation and function effectively when the boiler tubes are in spaced relation. However, in boiler wall tubes, the boiler tubes are positioned in closely spaced relation and are interconnected by webs to form a continuous boiler tube sheet or wall. The tools disclosed in the above-mentioned patents are not especially adapted for use with boiler tubes forming a boiler wall.
In addition, U.S. Pat. Nos. 4,846,391 and 4,936,500, both issued to Gary McClure, discloses various embodiments of boiler wall tube tools that clampingly engage the respective tubes to facilitate welding in the repair of a wall rube or tubes. The '391 patent discloses a boiler wall tube tool having a pair of opposed clamp members that includes a pair of recesses to engage adjacent ends of a pair of boiler wall tubes on the opposite sides of a juncture between adjacent ends. The tool includes means for moving the clamps toward on another, thereby generating a secure clamp engagement between the clamps onto the respective tube or tubes. Moving means is described as a handle and a mounting bar that is inserted through each of the clamps. The '500 patent is a variation of the '391 patent in some respects, and specifically discloses a boiler wall tube tool that is bolted directly onto the boiler tube wall as opposed to utilizing a handle and mounting bar combination disclosed in '391. The embodiments disclosed herein provide the user with the ability to use the invention on variously sized/dimensioned tubes and allows for greater access to the weld site, increasing the ease and efficiency of welding of boiler tubes in the field.
Other prior art considered relevant to the present invention includes U.S. Pat. No. 5,481,793 (also issued to Gary McClure), U.S. Pat. No. 2,612,821 (issued to Skay), U.S. Pat. No. 6,007,029 (issued to Barringer et al.), U.S. Pat. No. 5,083,372 (issued to Polutnik), U.S. Pat. No. 5,044,075 (issued to Brennan et al.), U.S. Pat. No. 4,979,294 (issued to Bowman et al.), U.S. Pat. No. 6,308,921 (issued to Borzucki), and the group of U.S. Pat. Nos. 5,893,209, 5,974,642, 6,182,354 and 6,385,841 (all issued to Weeks).